Two types of new three-dimensional d–f heterometallic coordination polymers based on 2-(pyridin-3-yl)-1H Imidazole-4,5-dicarboxylate and oxalate ligands : syntheses, structures, luminescence, and magnetic properties

Two types of new d–f heterometallic coordination frameworks, [Ln2M(μ3-HPyIDC)2(ox)2(H2O)4]·4H2O [Ln = Sm, M = Co (1); Ln = Sm, M = Fe (2); Ln = Eu, M = Co (3); Ln = Eu, M = Fe (4); Ln = Gd, M = Co (5); H3PyIDC = 2-(pyridine-3-yl)-1H-4,5-imidazoledicarboxylic acid; ox = oxalate] for type I and [Ln2Ag3(μ5-PyIDC)(μ6-PyIDC)(μ2-OH)(ox)(H2O)2] [Ln = Sm (6); Gd (7); Tb (8); Dy (9)] for type II, were prepared under hydrothermal conditions and structurally characterized. Complexes 1–5 are isostructural, exhibiting three-dimensional (3D) heterometallic networks with pcu topology based on the linkages of two-dimensional (2D) lanthanide–oxalate layers and pillar-like M(HPyIDC)2 (M = Fe, Co) subunits. Complexes 6–9 are also isomorphous and display another type of 3D heterometallic coordination framework built through the connections of 2D lanthanide–oxalate layers and one-dimensional (1D) Ag2(PyIDC)2 chains. Interestingly, the oxalate ligands in complexes 6–9 are produced by the in situ decarboxylation of the H3PyIDC ligand in the presence of 4,4′-bipyridine (4,4′-bpy). The photoluminescence, thermal stabilities, and magnetic properties of the selected complexes were also investigated